The present invention relates to a stress measuring method and systems, more specifically, a stress measuring method and system for measuring a stress distribution in a microscopic region.
Elements, such as transistors, interconnections, etc., containing the peripheries, are formed of many kinds of polycrystalline substances and amorphous substances. In the vicinity of the interfaces between such substances of a plurality of kinds, various stresses are generated due to different thermal expansion coefficients of the substances, and the structures, and often the performances of the elements are changed. Then, in the fabrication steps and reliability evaluation steps, it is important to evaluate factors which could be stress sources irrespective of the crystallinity differences.
As methods for evaluating stresses of crystalline substances are known methods wherein signal changes due to strains of lattices are metered by X-ray diffraction, electron beam diffraction, Raman spectroscopic analysis using laser, etc. to compute stresses.
On the other hand, as methods which do not rely on the crystallinity of films are known a method wherein stresses are evaluated based on bowing changes of substrates, a method wherein stresses are evaluated based on photoluminescence signal changes given by laser, or other methods. However, the former can evaluate only an average stress of a substrate but cannot evaluate local stresses in electronic device structures, etc. The latter cannot, in the principle, evaluate stresses in submicron-regions, because the converging ability of lasers is about 1 μm.
The related arts are disclosed in, e.g., Reference 1 (Japanese patent No. 3285157), Reference 2 (Japanese published unexamined patent application No. Hei 04-179215), and Reference 3 (Japanese published unexamined patent application No. 2004-327843).
As described above, presently there is no method for evaluating stresses of amorphous substances forming microscopic devices. The stress evaluation of an amorphous substance is made by estimating a stress, based on a stress evaluation result of a crystalline substance neighboring the amorphous substance or by estimating a stress, based on a calculation result given by finite element method. Thus, it is difficult to correctly evaluate stresses in microscopic regions of amorphous substances by the conventional measuring methods. Stress measuring methods which can correctly evaluate stresses in microscopic regions of amorphous substances have been required.